What do you mean by a scatter diagram? How is correlation measured by this method?
A scatter diagram : A scatter diagram is a simple visual method for getting some idea about the presence of correlation between two variables. In a scatter diagram, we plot the values of two variables as a set of points on a graph paper, the cluster of points is called scatter diagram.
Drawing of a scatter diagram involves following steps:
1. Writting down the independent variables on X axis.
2. Writting down the dependent variables on Yaxis.
3. Points with the help of given data are marked on the graph paper.
4. When the plotted points show some trend upward or downward, we know that there is some correlation between the variables. When the trend is upward, the correlation is positive. On the other hand, when the trend is downward, the correlation is negative as shown in fig.
